Posted by peter |
… to hack wordpress to support eaccelerator
cache or memcached. Well honestly speaking if….
Fragmentation over time – Over time
Query Cache might get fragmented, which … whole objects rather than individual
queries.
No control on invalidation Table …
Posted by Vadim |
… table has column level privileges – function
query_
cache_send_result_to_client just …’;
and under user ‘vadim’
Before
query execution:
mysql> show global status like …that proves the initial assumption – the
query that includes tables with defined …
Posted by
Vadim @ 11:25 am ::
bugs,
tips ::
Posted by peter |
… had number of consulting projects with MySQL
Query Cache being source of serious problems. One would see
queries both for MyISAM and Innodb tables …of invalidations like tens-hundreds of thousands
queries being invalidated by single insert – …
Posted by
peter @ 1:40 pm ::
tips ::
Posted by peter |
… line client is known to optimize
queries sometimes by skipping “unnecessary” comments.
… the following about MySQL 5.0
Query Cache:
Whitespace at the start of…with different comments are considered different
queries (it is not stripped before hashing…
Posted by peter |
… in transaction it becomes uncachable by
query cache until that transaction is … course such implementation is rather restricted.
Queries outside of transactions well could … hard to implement using current
query cache infrastructure. With current approach …
Posted by
peter @ 2:30 pm ::
Innodb ::
Posted by peter |
…by Konstantin Osipov we should finally get
Query Cache working with prepared statements in … to have fast prepared statements without
query cache or no prepared statements with …
Would this make me use/advice
Query Cache more ? Not really. There are …
Posted by Baron Schwartz |
… and we can’t find any
queries that would seem to trigger outages:… mentioned above were caused by scalability/concurrency/locking problems in the
query cache. (One was on Windows, and…lockups, you might try disabling the
query cache, and see if that solves…
Posted by
Baron Schwartz @ 7:46 pm ::
tips ::
Posted by peter |
… be performance bottleneck, assuming PHP opcode
cache is not used. Also different … database multiple times. Examining MySQL full
query logs from many applications seeing … (TCP/IP) 9900
MySQL
Query Cache (Unix Socket) 13500
Selecting from …
Posted by
peter @ 8:00 am ::
lamp ::
Posted by peter |
… you invalidate or remove objects in
cache once underlying information is updated. This… be invalidated – approach used by MySQL
Query Cache is too coarse invalidating a …thing about this approach is – you
cache operations have constant complexity – you do…
Posted by
peter @ 5:15 am ::
lamp ::
Posted by peter |
… because SQL_NO_
CACHE only bypasses
query cache but it has … only lightly, the hardware IO
cache may however cause dramatic difference…. to clean all of the
caches. You can do FLUSH TABLES…course to reboot.
For Hardware
Caches it is more hardware specific…
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